The invention relates to electrical machines. More specifically, the invention relates to an auxiliary system including a plurality of ac motors that are powered by an electric generator.
Gas turbine engines provide propulsion for aircraft and certain ground-based vehicles. In addition to providing the propulsion, the gas turbine engines also drive hydraulic pumps, fuel pumps and other auxiliary devices on the aircraft and ground-based vehicles. Typically, gearboxes transmit shaft power of the gas turbines to the auxiliary devices.
Gearboxes are heavy and noisy. They also require lubrication and all of the maintenance demands of a lubrication system. Additionally, gearboxes can be unreliable.
These problems are compounded for gas turbine engines that drive multiple auxiliary devices. Additional gears are needed for driving the additional devices, thus adding additional weight, noise and unreliability. There are additional problems as well. If some of the auxiliary devices need to be switched in and out, mechanical clutches are added to the system. Moreover, adding auxiliary devices to an existing system would be difficult since the gearbox design would have to be modified.
Additional problems can arise because the auxiliary devices cannot be located remotely from the gearbox. When a pump is located at the gearbox and its hydraulic load is located remotely from the gearbox, a hydraulic line is extended from the pump to the hydraulic load. The hydraulic line has the potential for leakage, which presents a fire risk among other things.